Adjustable locking mechanism for breakdown firearms



March 24, 1931. F. F. BURTN ADJUSTABLE LOCKING MECHANISM FOR BREAKDOWNFIREARMS Filed March 21. 1930 claims.

Patented Mar, 24, 1931 FRANK BURTON, OF 'OUNT CABI IEL, GONNECTGUT,ASSIGNOB 'ISO WINCHESTER BEPEATING ARI'vIS COMPANY, OF NEW' HAVEN,CONNECTICUT, A CORPORATION OF ADJUSTABLE LOCKING MECHANISM FOR BREAKDOWNFREARMS Application filed March 21, 1930. i Serial No. 437,'776.

This invention relates to an improvement in adjustablelocking-mechanisms for breakdown firearms, such as shotguns and rifies.

The main object of this invention is to provide a hreakdown fircarm withan adjustable smooth-acting and readily-releasable locking-mechanismwhich will effectively and securely hold the barrel-unit thereof inoperative position with respect to the frame-unit, despite wear and theeffects of recoil and counter-recoil of the arm.

With the above and other objects in View as will appear from thefollowing, my invention consists in an adjustable lookingmechanism forbreakdown firearms characterized by a manually-retractable springpressedlooking-bolt mounted in the frameunit and provided with a lookingcam-surface coacting with a complementary camsurface upon thebarrel-unit and an adjustable stop-abutment positioned so as to limitthe wedgng tendencies between the two said looking cam-surfaces.

My invention further consists in an adjustable locking-mechanism forbreakdown firearms characterized as above and having certain otherdetails of Construction and combinations of parte as will be hereinafterdescribed and particularly recited in the Tn the accompanying drawings:Fig. 1 is a broken View, partly in side elevation and partly in centrallongitudinal,

section, of a double-barreled breakdown shotgun provided with myimproved adjustable looking-mechanism;

Fig. 2 is a broken View in transverse horizontal section taken on theline 2-2 of Fig. 1;

Fig. 3 is a broken view in side elevation of the rear end of thebarrel-unit;

F ig. 4 is a face view of the rear end of the harrel-unt;

Fig. 5 is a detached view in side elevation of the looking-bolt; and

Fig. 6 is a detached underside view of the looking-bolt.

The embodiment of my invention herein chosen for illustration is, asshown, .installed in a double-barreled breakdown shotgun,

though it is obvious that the use of my invention is not so limited,since it may be advantageously employed in connection with other typesof breakdown firearms.

Theshotgun shown comprises the usual frane-body 10 formed at its bottomedge with a forward extension 11 which in turn is forned with alongitudinal vertically-arranged slot or passage 12 open at its upperend and closed at its bottom end bythe forward end of a trigger-plate 13having a trigger-guard 14 within the looped form of which a pair oftriggers 15 are located.` The frame 10, as is usual in firearmConstruction, is Secured to the forward end of a butt-stock 16 in anyapproved manner.

To provide for pivoting the barrel-unit which comprises in the main apair of barrels 17 and a foreend 18, as well as other incidentalfeatures, I provide a transverse trunnion-pin 19 commonly referred to asa joint pin and eXtending across the slot 12 in the extension ll of theframe-body 10 in the opposite side-walls of which it is supported in theusual manner. This trunnon-pin is partly embedded, so to speak, in theforward wallof the slot 12 but in its central' part it has the majorportion of its circumference rearwardly eXposed within the forward endof the said slot, as clearly shown in Fg. l of the drawings.

The barrel-unt is provided in its underside with alongitudinally-arranged centrally-deending lug 20 adaptedto fit withinthe slot 12 of the frame-body 10, as clearly shown in Fig. l of thedrawings. The forward end 'of the lu 20 is formed with a forwardlyfacingsu bstantially-semicircular transverse notoh 21 adapted to rock upon thetrunnionpin 19 before referred to.

The lower forward corner of the extension 11 of the frame 10 is roundedofi as at 22 concentrically with the trunnion-pin 19 so that the shoe 23of the foreend 18 will snugly i fit against the frame-bo dy 10 in allpositions ture of the surface 22 of the extension 11 and resulting inthe torniation of a reiatvely-v sharp toe 25. u

For the purpose of hnnting the breazdown movement of the harrel-uniowithrespect to `the .t'rame-body 10, I emnloy a floating barrel-stop-bar 26ino unted 'for vertical move ment in a transverse slot 27 in the beforereterred to and to haveits setting lug 34 formed in its'outer ot areciprocating 'b'arrel looking-bolt 32 niounted for movement in ahorizontal bore 33, formed in the frame-lody 10 andhaving its forwardene intersec ing the rear end of the vertical slot 12, bet-o 'ereterredto.

The main portion oi' the looking-bolt 32 is of oylindrcal form and isprovided at its rea? end with a horizontal laterally-ofiend wthaooupling-notch 35 tor the reception of a cylindrically-contouredoperating finger 36, depending froni the under' tace of a substan- Vtially disk-like' Operating-head 37 having a ;looking-bol.,

` square axal bore 38 for the reception* of the squared lower end of thevertical shank 39 ot' a finger-iever 40, to which it' is Secured by adianetrical pin 41.

The finger-lever 40 extends rearward froni the shank 39 and is located,as is usual in breakdown firearns upon the upper face of the treme-body10 and normally extendng over the butt-stock 16.

For the purpose. of normally urging the Operating-head 37 together withthe shank 39 andfinger-lever 40 in a clockwise direction, as viewed inFig. 2, andhence urging thenose 31 of the looking-bolt 32 into the notch28 of the lug 20, I employ a phn'ger &2 reciprocatng in arearwardly-opening socket 43 formed inthe frame-bo-dylo (Fig. 2) andhaving a rearwardly-extending thrustnose 44 of reduced diameter;engaging a radial thrust-face 45 upon the Operating-head 37. The forwardend of the plunger 42 is formed with an axial stem which is encircled bya helical spring 4:7 hearing, at its rear end, against the forward endof the said i plunger and, at 'its forward end, hearing against thebottom wall 48 of the socket %3 before referred to.

From the foregoing, it will be seen that the k: t 32 is constantly urgedby the spring 457 into its forwardly-extended position in which itslooking cam-'surface 30-is eugaged with the similar surface 29 upon thebarrel-lug 20 with the efi ect otfirnly looking the barrel-unit in itsclosed position and,

m'et/,320

well knownin the art of breakdown firearms.

he up per forward end of the lookingnose ;of the looking-bolt 32 isrearwardly and upwar'diy sioped to form the cam-surface &9 adapted to'be engaged by a complenientary cam-surface 50 forned at thelower rearcorner ot the lug 20 of the barrel-unit for the purpose ofautoniatically-retiring' the sai-d bolt, should it per chance be n aprojected position when the barrel unt 1s swung downward from theposition'in which. it is' shown' by broken lines in Fig. l-tothe'p'ostion in which it is shown by tulL-lines in the same figure. i

- n the operation of thebreakdownshotinrention, the user when desiringto load the piece, swings the fing'er lever 40 and,

through the intern'iediary of the-parte 39', '37, nq

oo,` 35 and 3% retracts the harre'llocking-bolt ni'the' notch 28 of; thelug 20, thus"per- 'the barrel-unit tobe swung into its hrolendownposition in 'which it is shown 'by broke-n lines in Fig. 1.-

iframe-unit in the usual Inanner' and as the said barrel-unit;approaches its home posiv iton, the bol-t 32 will be forciblyprojectedforward by the spring 47 so= as to engage the looking canrsurfac e 30'of its nose 31 'with the siniiiar surface 29 of the l ug20, with theeflect of lockingthe barrel-'unt in: its' operative pos tion' withrespectto the hame-unit.

.` o 5 y v V lo check the wec gng or ammng -acton between the lookingcam surfaces- '29' and' 30' 1 y i when the looking-bolt s'pro1ectedforward',

as above describedyl provide anadj-*ustable stop-abutment in the form ofa screw 51,

having a fiat head 52 and mounted' in a threaded-bore 53 preferablylocated in the lug 20. The rear end of the threaded-bore 53, justreferred to, is co-unterbored as 'at' 54 to provide clearance for' the'head 52 'of the' said screw 51, which -iatt'er is engaged, as shown inFig. 1, by the forward end of the lockinbolta'32 to limit the torwardmovement -oI the same. i

Heretofore, manufacturers have been'eon- .which is preferable torsecure-looking 'ofthe a distance su'fiicient to disen'gage its nose Eter the loading ofthe piece, the user' swngs the barrel umt into linewith the:

` gun heroin chosen tor theillustration'e-tmyi.

piece a marked wedging or jamming'action takes place between thesaidsurfaoes, due to the forward snapping *of thebolt under the urge' ofits spring and thefurther forward urge imposed upon the said bolt Whenthe piece recoils. With a bolt so jammed, a Very oonsiderable force mustbe eXerted upon the finger-lever 40 in order to overcome this jammingaction and retract the bolt. On the other hand, when the coactingoam-surfaoes are steeply inclined, the counter-reooil of the piece wouldtend to partially retract the locking-bolt and permit a slight, but nonethe l less objeotionable, partial breakdown move*- ment of thebarrel-unit.

By means of my invention, I am enabled to employ thelooking'oan-surfaoes'29 and 30 or their equivalent which have arelativelyslight slope and are, therefore, advantageous for the reasonsabove stated, and efieotively prevent any objectionable wedging orjamming action by means of the checking action of the adjustbalestop-.screw 51.

Should the looking cam-surfaces 29 and wear to a degree suffioient topermit appreiable freedom between the frame-unit and barrel-unit when intheir locked positions, such wear may be compensated :for withoutendangering a jamming action by threading the screw 51 forwardsufiiciently to permit the close engagement of the said cam-surface&

It will be understood by those skilled in the art that my invention mayassume varied physioal forms without departing from my inventive conceptand I, therefore, do not limit myself to the specific embodiment hereinchosen for illustration, but only as indioated in the appended claims.

I claim:

1. In a breakdown firearm the combination with a relatively-pivotediframe-unit and barrel-unit thereot, of a manually-retirablespring-pressed barrel looking-bolt mounted in the said rame-unit; alooking cam-surface 'ormed upon the said barrel looking-bolt; aoomplementery looking cam-surface tormed upon a portion of the saidbarrel-unit in position to be engaged by the said cam-surface i of thebarrel looking-bolt; and an adjustable stop-abutment for the said boltpositioned to limit the movement thereof under the urge of its spring toprevent the wedging of the two said looking cam-surfaces. v

2. In a breakdown firearm the combination with zi relatively-pivotedframe-unit and barrel-unit thereof, of a reciprocating manuallyretirablesprng-pressed barrel looking-bolt mounted in the said frame-unit; alooking cam-surface formed upon the said reciprooating barrellooking-bolt; a oomplementary looking cam-surface formed upon a portionof the said barrel-unit in position to be engaged hy the saidcam-surface of the barrel lookingholt; and an adjustable stop-abutmentfor the said reoiprooating bolt positioned to limit the movement thereotunder the urge of its spring to prevent the wedging of the two saidlooking oam-surfaces.

3. In a breakdown firearm the combination with a relatively-pivoted:iframe-unit and barrel-unit thereof, of a manually-retirablespring-pressed barrel looking-bolt mounted in the said {rame-unit; alooking cam-surface tormed upon the said barrel looking-bolt;` acomplementary looking cam-surface formed upon a portion oi: the saidbarrel-unit in position to be engaged by the said cam-surface of thebarrel looking-bolt; and an adjustable stop-abntment tor the said boltmounted in the said harroi-unit and positioned to limit themovementthereof under the urge of its spring to prevent the wedging ofthe two said looking can-surfaoes.

l. In a breakdown firearm the oombination with a relatively pivotedframe-unit and barrel-unit thereof, of a barrel-lug depending from thesaid burrel-unit; a manually-retirable spring-pressed barrellooking-bolt mounted in the said rame-unit; a looking cam-surface formedupon the 'said barrel looking-bolt; a oomplenentary looking camsur'aoetormed upon the said barrel-lug in position tobe engaged by the saidoam-surfaoe of the harrel looking-bolt; and an adjustable stop-abutmentpositioned to limit the movement of the said bolt under the urge of thespring thereof to prevent the wedging of the two said lookingcam-surface&

5. In a breakdown firearm the oombination with a relatvely-`pivotedframe-unit and barrel-unit thereof, of a barrel-lug depending from thesaid burrel-unit; a manuallyretirable spring-pressed barrel looking-boltmounted in the said frame-unit; a looking cam-surface formed' upon thesaid barrel looking-bolt; acomplementary looking cam surface formed uponthe said barrel-unit in position to be engaged by the said cam-surfaceof the barrel looking-bolt; and an adjustable stop-abutment mounted inthe said barrel-lug and positioned to limit the movement of the saidbolt under the urge of the spring thereof to prevent the wedging of thetwo said looking oam-surfaces.

6. In a breakdown firearm the combination with a relatively-pivotedrame-unit and barrel-unit thereof, of a barrel-lug depending from thesaid barrel-unit; a manually-retirable spring-pressed barrellocking-bolt mounted in the said treme-unit; a looking cam-surfaceformed upon the said barrel looking-bolt; a oomplementary lookingcam-surface formed upon the said barrelunit in position to be engaged bythe said cam-surface of the barrel looking-bolt; and anadjustablestop-screw mounted in the said barrel-lug and positioned to limit themovement of the said bolt under the urge of the spring thereoi toprevent the wedging of the two said looking cam-surfaces.

7. In a breakdown firearm the oombination with a relatively-pivotedframe-unit and; barrel unt thereof, of a barrel-lug de ending from' thesaid barrel-unt; a 'manually retrable sprng-pressed bar'e looking boltmcunted in the said treme-unit; a lockng cam-surface formed'upon theseid ba'rel lckng-bot; afcomplementary lockng earnsurfaee fol-med uponthe said barre-unt in position to he eng-&ged by the said cam-eurface ofthe burrel Making-bolt; a thretdedbore formed in thesadbarre-mg abovethe looking cam-surface thereof; and an adjustabe step-screw threadedinto the said bore in position to limit the movement of the sai-:1 boltunder the urge of the spring thereof to prevent the Wedgng of the twosadlcking cam-surface&

8. n a breakdown firear m the combineten With a'relat vely-pvotedrame-unit and berrel-unt thereot, of a barrel-lug depending from thesad'barrel-unt; a manuafly- 'etrable reeprocatng sprng-pressed barreloekng-bolt monnted in' the hame-unit; a downwa'dy-f cng lookingcam-surface formed upon the se barrel looking-bolt; an upwa'dly-facngcomplementary cam-surface forme& upen the said barreI-hg in position tohe eigged by the said cam-surface of the recp'ocatng barr l *a kim -be*1 suhs n -h e 4 v J, c u u y orznea threecechbore ;owned nthe saclbarre-lug above the lockmg cam-surface thereof; and :n ad ustabestop-screw threeded into the sad bore n poeten to lumt the movement OI"the seid bot under the urge of the spring' thereof to preventthe Wedgngof the two sad leckmg cam-surface& In testmeny whereot';

I specficaton.

FRANK F. BURTON.

have signed this

